This competing continuation application seeks funds to perform a randomized controlled trial comparing a stepped care approach to a standard behavioral weight loss treatment (BWL) for obese patients with binge eating disorder (BED). Although cognitive behavioral therapy (CBT) is currently the best-established treatment for BED, it does not produce weight loss in this obese patient group. BWL is a viable treatment option given its effectiveness, its wider availability, and need for less specialized training than CBT. In this study, subjects will be randomized to either stepped-care or to standard BWL for 6 months. In the stepped-care arm, following one month of BWL, patients are stratified by whether or not they show an early rapid response to BWL. In this application we provide findings from four controlled trials showing the robust predictive utility of rapid response for the purpose of subsequent treatment assignment. Rapid responders are then randomized to receive either the sibutramine or placebo in addition to continuing to receive BWL for another 5 months. Patients who do not show a rapid response to BWL are switched to guided self-help CBT (CBTgsh) and are randomized to also receive sibutramine or placebo for another 5 months. The BWL in both the stepped-care arm and standard treatment arm will be the same. BWL and CBTgsh will follow established manualized protocols. Medication conditions will be double-blind. Changes throughout the course of treatments will be evaluated, including an assessment at one month to ascertain early treatment response. Major outcome assessments will be performed by independent evaluators at the end of treatments (6 months) and at 6- and 12-months following treatments (12 and 18 months after randomization). Comprehensive evaluations will assess both binge eating and obesity and their associated outcomes and will examine the durability of the treatments. The repeated assessments will also allow for exploration of mediators and moderators of outcomes and estimates of cost-effectiveness. Public Health Relevance: This R01 is a randomized controlled trial comparing a stepped care approach to a standard behavioral weight loss treatment (BWL) for obese patients with binge eating disorder (BED). Subjects will be randomized to either stepped-care or to standard BWL for 6 months. Subjects will be followed up for 12 months after treatment. This study will provide important information about the effectiveness and durability of these treatment approaches for obese person with BED.